1. Field
An aspect of the embodiments discussed herein is directed to a semiconductor device including a plurality of transistors.
2. Description of the Related Art
Not only high-performance design but also miniaturization and high degree of integration are promoted on semiconductor devices.
A static random access memory (SRAM), as one type of volatile memories, is free from a refresh operation, and operates at a high speed. The SRAM finds applications in a variety of apparatuses. The SRAM is typically constructed of parallel unit cells, in which gate electrodes of transistors are linearly disposed in parallel to each other on a plane and active regions are linearly disposed in parallel to each other and intersect the gate electrodes.
Arrangements of the SRAM unit cells are discussed in Japanese Laid-open Patent Publication Nos. 6-350053, 8-37241, 9-321152, and 10-335487. In the disclosed arrangements, the gate electrodes and the active regions are slant to mutually intersecting word lines and bit lines at an upper layer in plan view.
The size reduction and high degree of integration are introduced in the SRAM unit cells by reducing the gate electrodes and active regions in size, narrowing the spacing between the adjacent elements, and extending the elements in an inclination angle.
Demand for even further miniaturization and higher degree of integration is mounting as the SRAMs find applications in a wider range of fields and have a larger memory size.
In each transistor forming the SRAM, a contact electrode is disposed in each of active regions on both sides of a gate electrode in order to establish electrical connection with an upper wiring layer. A distance between the gate electrode and the contact electrode is already narrow in the current design of the SRAM, and a position margin permitted therebetween is very small. It is desirable for conventional techniques to promote further miniaturization and higher degree of integration with position margin assured.
The same phenomenon may occur not only on the SRAM but also on other semiconductor devices composed of a plurality of transistors.